Protostome vs Deutrostomes

- Deuterostome = Second Mouth
- Two groups differ by embryonic development
Deuterostome clade
- Phylum Echinoderms (Inverts) & phylum Chordata (Vertebrates)
- Independent evolution of each group
- Deuterostome = Developmental similarities
- radial cleavage
- anus from blastophore
- HOWEVER: other basal animal phyla share some of these traits
- Deuterostomes now defined by DNA


Sexual Reproduction in animals results in diploid zygote


Phylum Echinoderms


- Translates to ‘Spiny Skin’
- sea stars and urchins
- slow moving and marine
- adult = radial, larval = bilateral
- Thin epidermis covered in hard plates
- often with bumps or spines
Phylum Echinoderms


- Translates to ‘Spiny Skin’
- sea stars and urchins
- slow moving and marine
- adult = radial, larval = bilateral
- Thin epidermis covered in hard plates
- often with bumps or spines
- Possess a unique water vascular system
- flexible hydraulic canals = tube feet
Phylum Chordata (mostly vertebrates)
- All chordates share 4 traits
- Some only in embryo stages
- Notochord
- Dorsal, hollow nerve cord
- Pharyngeal slits
- Muscular, Post-anal tail
- 2 invertebrates groups that are more related to vertebrates
- Cephlachordata (lancelets)
- Urochordates (tunicates)


Lancelets and Tunicates

Vertebrates are chordates with a backbone
- Possess skeletal and nervous systems
- simple to complex backbones
- lots of unique genes (eg. HOX)
- Derived trait = neural crest
- special cells near neural tube in embryo
- give rise to many vertebrate traits
- e.g.. teeth, skull cartilage, etc

History of backbones: ~500 million years old
- Evolved while predators where developing
- Cambrian period
- Ocean origins (first 150 mya)
- Vertebrate: series of bones that make up the vertebral column
- Vertebrates colonized land 365 mya
- Amphibians
- Reptiles (w/ birds)
- Mammals

Hagfish and Lampreys
- Only members of vertebrates without jaws
- Have rudimentary backbones
- Hagfish escape by releasing slime
- researched to stop bleeding in surgery

Hagfish and Lampreys
- Only members of vertebrates without jaws
- Have rudimentary backbones
- Hagfish escape by releasing slime
- researched to stop bleeding in surgery
- Many Lamprey are parasitic on fish

Vertebrates with jaws


Sharks and rays
- ‘Cartilage fishes’: skeletons mostly cartilage
- originated 400 mya
- often with calcium
- Streamlined body for swift swimming
- Birth via eggs or young develop inside mother
- Modern species diversity shrinking

Ray-finned and Lobe-finned fish
- Phylogeny: large new vertebrate group with bony endoskeletion

Ray-finned and Lobe-finned fishes (lung on phylogeny)
- Important derived traits for fishes:
- Ray-finned: bony rays that support fins
- Lobe-finned: rod-shaped bone surrounded by muscle in fins
- lungfish, Coelacanths, tetrapods

Evolution of Tetrapods
- Fins gradually evolved into limbs
- Tetrapods colonized land 365 mya
- move away from fish-like vertebrates
- Tetrapods derived trait = limbs with digits
- supports weight
- digits efficiently support movement

Tiktaalik fossil (aka ‘Fishapod’)

- New selection of many terrestrial traits
- head separated from body by a neck
- add vertebrate to allow head to swing
- bones of pelvis fuse to backbone
- many species lost gills (became ears)
Amphibians (frogs and salamanders)

- Include salamanders, frogs and caecilians
6,000 species
- caecilians lost legs
- Rely on skin for gas exchange
- Name means ‘dual life’
- some have aquatic tadpole larvae
- more related to metamorphosis;
- gills → legs, lungs, eardrums
Amniotes: tetrapod with terrestrial egg (also rib cage)


Reptiles
- Lizards, snakes, turtles, crocs and BIRDS
- many extinct groups
- small (16mm) to large (12m)
- Most reptiles are ectothermic

Reptiles
- Lizards, snakes, turtles, crocs and BIRDS
- many extinct groups
- small (16mm) to large (12m)
- Most reptiles are ectothermic

The origin of birds (members of the reptile family tree)


Mammals
- Large adaptive radiation post dinosaurs
- predators, herbivores, flying, aquatic
- Monotremes = platypus (egg laying)
- Maruspials = pouched mammals
- Eutherians = placental mammals
- Derived Trait: Mammary glands
- produce milk for offspring
- Derived Trait: Hair
- Derived Trait: Kidney
- waste removing/water saving organ
